The guys I hired did a hell of a lot more than walk around and look at stuff
They took apart part of my furnace, HRV, cleaned my filters and showed me how to do it, removed the cover and inspected my entire electrical panel, tested my sump/lift, measured grades around the property, measured drafts around exterior doors, used infra-red to make sure my in-floor heating was all working properly, etc.
They'll never catch absolutely every little thing but for how cheap it is relative to the home cost, and for how much they do tell you, it's worth it IMO. Honestly the amount of questions I asked them and the education I got was worth the $500 alone haha.